Back in the summer of 2007, I was ready to call it quits after a year-and-a-half with the ubiquitous Behringer DSP1124 Feedback Destroyer I was using to equalize my subwoofers.

It had always been a love/hate relationship with the BFD. Certainly, I loved the fabulous sound I was able to achieve by accurately smoothing my subwoofer’s response. But I wasn’t particularly fond of the way it looked, especially since everything else in my system is black.

Being a fan of analog parametric equalizers, I was accustomed to their easy-access controls for frequency, gain, and bandwidth. By comparison, I found the BFD’s interface to be ridiculous and cumbersome. Another irritation was that once the BFD is set, you can’t tell what your filter parameters are without a lot of button pushing and wheel turning, and then referring to a secondary source to translate bizarre designations like “40 Hz +10” to an actual numeric frequency. With an analog parametric you have all filter settings available at a glance.

On the other hand, the BFD’s ability to save settings to memory was a decided advantage over analog equalizers. And there was an upside to the aggravation of accessing filter settings – it also meant they were safe from accidental changes or intentional tampering (filter settings on an analog parametric are all-to-easily altered – just twist a knob). So, I could certainly see the benefit in staying with a digital equalizer. Just not this garish and unintuitive one.

So, I embarked on a search-and-destroy internet search to see if I could find some obscure black-faced digital parametric equalizer from the pro audio world that had escaped the notice of the home theater set. Eventually I came across a vintage model from Yamaha that fit the visual requirements. A review of the on-line manual showed the YDP2006 fit the functional requirements as well: A two-channel model with six parametric filters per channel that could also be configured for twelve-filter mono operation. All filters could be assigned anywhere in the audio spectrum, a critical feature for any parametric equalizer dedicated to a subwoofer. And to my delight, the manual showed that filter adjustments were accomplished with digital encoder knobs for frequency, bandwidth, and gain that mimicked analog operation.

It looked like I had a winner. Now, to find one. I did a saved search on ebay and in a week or so one appeared for auction. It didn’t escape my notice that the seller, who had been using it in his recording studio, extolled the YDP2006’s sonic capabilities with much enthusiasm, as well as its processing power.

Although I acquired this equalizer simply because it was easier to use and a better visual match with the rest of my system, the Yamaha proved to be an absolutely stunning piece, with features and flexibility unmatched by the Behringer DSP1124 (currently designated as FBQ1000), and performance unmatched even by the superb AudioControl C-131 1/3-octave equalizers I had been using in my system for the previous twelve years.

OVERVIEW

General Description
The YDP2006 is a compact 1 rack-space package (compact in that most stereo analog parametrics are 2-space units) that, as best as I can tell, was in production from about 1996 to 2002. It was an expensive equalizer, with a list price in the neighborhood of $2300. The price at least got you an impressive pedigree: Yamaha was the first company to offer a digital parametric equalizer to the pro audio market, way back in 1987 when they introduced the model DEQ7 that featured 16-bit A/D-D/A converters. The YDP2006 was a third-generation product, benefiting from more advanced 20-bit A/D-D/A converters and an improved user interface, among other things. Yamaha concurrently offered a digital 1/3-octave equalizer, the YDG2030. Following an industry trend, Yamaha has offered no successor for these equalizers since they went out of production (although strangely they continue to offer a mediocre analog 1/3-octave equalizer that’s been in their product line for over 20 years). Other companies also offered digital equalizers during that era, many with additional features such as limiters and compression, which have also been discontinued. With the exception of Behringer and perhaps a few others, the trend in the pro-audio industry has been to roll EQ functions into digital speaker-management processors and more lately, directly into digital mixing consoles.

As the steep list price would indicate, the YDP2006 is professional-grade piece whose build quality makes the BFD look and feel like a toy by comparison. Cabinet construction is medium-gauge steel and it weighs a substantial 10 lbs., which is more than twice the BFD’s weight. The YDP is physically large as well, fully 13” in depth compared to the BFD’s trim 7-1/2”. On the back panel are heavy-duty, cast-metal XLR connectors with locking mechanisms, instead of the BFD’s plastic non-locking fare. Even the Yamaha’s power switch has a more substantial feel and sound than the BFD’s when engaged. This is not to disparage the Behringer; at more than twenty times the price, we would certainly expect the Yamaha to be a more robust product. The YDP’s appearance is a bit “industrial” compared to most consumer home audio components, but nevertheless it is much better looking than the BFD, in my opinion.

The YDP2006’s front panel features three banks of buttons. One bank provides selection of the left or right channels for filter adjustments, a bypass switch, and access to the equalizer’s menu (which Yamaha calls “Utilitiy”) to set various operating parameters and features. Another bank is dedicated to accessing and storing the equalizer’s memory settings. The third bank independently turns each of the six filters off and on, subject to the main bypass button. LEDs indicate which filters are engaged, a nice feature that many analog parametric EQs have.

And probably my favorite feature, three knobs Yamaha calls “rotary encoders” for setting filter parameters. They are logically labeled “F” (frequency), “G” (gain) and “Q” (bandwidth), in traditional analog-parametric fashion. The same encoder knobs are also used to set other programmable parameters as well.

A large dual-mode LCD screen shows the status and parameters of any filters in use. The screen’s default mode is a graphic display that shows the electronic frequency response of all filters that are engaged (i.e., deviation from flat response). An optional screen mode, accessed by pressing the “PEQ” button, offers an itemized list of all filters, showing numeric values for frequency, gain and Q settings. With either mode, it’s certainly nice to be able to review filter settings quickly and easily. In addition, twin level meters feature green, orange and red (clip) elements, and a numeric read-out indicates the programmable memory position in use.

Rounding out the front panel controls is a concentric analog knob that sets the input level for both channels. Current-production pro-audio digital processors, which feature 24-bit A/D-D/A converters, have so much dynamic range in the digital realm that manufacturers have all but done away with input level controls. However, with the YDP’s less-capable 20-bit converters, such a control can be useful to insure the best signal level and quietest operation. In theory at least. In practicality, considering the YDP’s stellar noise characteristics, input levels shouldn’t ever be a concern. I just leave mine in the “0” position.

In addition to the aforementioned heavy-duty XLR audio connectors (there are no 1/4” or RCA connections), the YDP 2006’s rear panel carries other XLR and MIDI connectors that are most likely of no use for domestic applications. Switches for -20 dB or +4 dB operation are functionally identical to the -10 dBV and +4 dBu switches on the BFD’s back panel; however, the Yamaha assigns the switches to the inputs and outputs, instead of the left and right channels as the BFD does. A potential benefit of this arrangement is that with the switches in the proper configuration the equalizer can function as a line driver, substantially boosting the signal level to a downstream pro-audio amplifier. Alternately, the analog input control can give a +10 dB signal boost beyond its “0” setting. However, a noise penalty can be expected with either approach.

A common complaint with the BFD is the high intensity of the indicator LEDs. Most will probably agree that the Yamaha’s LED lighting is not as garish as the BFD. Both the input meters and LEDS for the function buttons and memory number muted in brightness compared to the BFD. The only glaringly bright LEDs are the ones indicating that the individual filters are on.

Features
Being digital, the YDP2006 has a lot of features that you would not find with an analog parametric EQ, or the BFD for that matter. Naturally some features are more relevant to professional users and applications; I won’t belabor the reader with a discussion on those.

As mentioned, the YDP is a stereo equalizer with six filters per channel. However, an option in the Utility menu can program the unit for mono 12-filter operation. Any filter can be set virtually anywhere in the 20 Hz – 20 kHz audio spectrum.

In addition: This is mentioned nowhere in the manual (!), but in stereo mode, filters #1 and #6 respectively can be switched to low- and high-shelving (in mono mode, this would be filters #1 and #12). This is accomplished by turning the “Q” encoder knob all the way to its widest bandwidth (i.e. smallest numerical Q). The display will show HSH (high shelving) or LSH (low shelving) when the filter has switched to shelving. As with regular parametric filters, the shelving filters can be set for virtually any turnover frequency desired.

The YDP2006 also has a bank of notch filters that can operate simultaneously with the parametric filters, which can (logically) be accessed via the “Notch” button. Those probably won’t be terribly useful to most home theater enthusiasts, but filters #5 and #6 are high and low pass filters, which certainly can be. Once again, either can be set virtually anywhere in the 20 Hz – 20 kHz audio spectrum. Yamaha doesn’t give any specs on these filters, and erroneously refers to them in the manual as “shelving HP [high pass] and LP [low pass] filters.” However, my crude measurements with sine waves and SPL meter indicate that they do not shelve but are constant-slope 24 dB/octave filters, most likely Butterworth alignments.

For those desiring absolute minimal background noise, the equalizer has a digital “Emphasis” noise reduction feature that can be accessed in the Utility menu. According to the specs, the Emphasis system will give a 4 dB noise reduction. However, Yamaha claims the equalizer has sufficient dynamic range so that the noise reduction should not be needed in most cases. I would agree. I did note a slight improvement in background noise with the Emphasis engaged, but not enough to make me want the additional processing added to the signal chain.

A delay function is also available that can be set in the Utilitiy menu to read in milliseconds, feet or meters. The delay increments are especially fine and can be set for fractions of an inch or millisecond. For instance, there are no less than 44 settings between 0 and 1 milliseconds, 1 and 2 milliseconds, etc. This is an especially useful feature that can serve to precisely time-align a subwoofer with the main speakers or the individual drivers in a bi- or tri-amped speaker system. It can also be useful in a home theater system if multiple YDP2006s are used for the main channels, delaying the center channel in relation to the mains (as it is often a bit closer to the main seating position than the side speakers), or if you have a problematic room that requires either the left or right speaker to be closer to the listening position than the other.

In addition to the front-panel input-level knob that operates in the analog realm, the YDP2006 features a digital attenuator. The manual is rather vague as to its purpose and use, but Yamaha describes it as a compensation for equalizer settings that result in an increase in “the overall gain of the sound,” which may result in “internal clipping... even if the level meters do not indicate clipping.” (If you’re getting the idea that the manual is rather poor, you would be right. It’s as bad or worse as the BFD’s manual.) Basically the situation is that (unlike the BFD) the YDP2006’s level meters are in front of the processing section and as such show only input level (as seen in the block diagram below). So, using a filter with say, +7 dB gain can make the equalizer clip before the input level meters hit red. A digital-domain attenuator is a really useful feature for this particular equalizer, since its 20-bit converters have 25 dB less digital-realm dynamic range than modern 24-bit processors. The attenuator can be set in 1/10 dB increments.

True to form, the manual’s explanation for actual use of the attenuator is maddeningly opaque, noting that it should be adjusted so that “the output level is the same as when the equalizer is bypassed.” In other words, match the bypassed and filters-engaged output levels by ear, or acoustically. It makes more sense to me to just dial in a value equal to that of your maximum boosted filter. In other words, in the example of the above-mentioned +7 dB filter (assuming you have no other filters with more boost than that) simply adjust the digital attenuator for -7dB. The input meters do seem to be calibrated conservatively, as I’ve pushed levels into the red and noticed no audible distortion. However, better safe than sorry.

The delay and digital attenuator features are accessed by pushing the “PEQ” button twice if you are in PEQ mode, or three times if you are in some other mode.

All equalizer, delay, attenuation etc. settings can be saved to any of 40 available memories, and they can manually be assigned names in the Utility menu – “Music,” “Action Movie,” “Mocha Latte,” or anything else that strikes your fancy. Also in the Utilitiy menu is a “Protect” function that can be engaged to lock down all settings to prevent accidental changes.

In addition, when the unit is turned off any settings currently in use are automatically saved and recalled when the power is cycled back on – like if you decided to make an adjustment on the fly to the memory preset you’re using. However, such adjustments are lost if you call up a different stored memory setting. In other words, if you wish to make your on-the-fly adjustments permanent, the memory setting you’re using must be re-saved.

Memory retention is made possible by a replaceable long-life lithium battery that is easily accessed with the top cover removed. Yamaha claims the battery is good for five years, which is a conservative estimate. I bought my first YDP2006 in 2007 – used, mind you – and have yet to replace a battery. Nevertheless, it would be a good idea to document your settings for the inevitable day that the battery does fail. The manual claims the display will give a low battery indicator when it’s on its last legs. Maybe someday I’ll actually see it.

PUBLISHED SPECIFICATIONS, ROOM EQ WIZARD MEASUREMENTS, AND GENERAL OPERATION

Published Performance Specifications
It’s a bit hard to do a point-by-point comparison of the Yamaha’s specifications to the Behringer’s, since they don’t use the same technical standards.

Despite its 20-bit converters, the YDP2006’s dynamic range is specified at an excellent 106 dB, improving to 110 dB with the Emphasis noise reduction. Behringer offers no dynamic range spec for the DSP1124, but its signal-to-noise ratio spec, given as > 94 dBu, taken with its +16 dB maximum signal input level, should translate to a dynamic range of ~110 dB.

For total harmonic distortion (THD), Behringer lists the DSP1124 as 0.0075%, while the Yamaha claims better than 0.01%, improving to .007% with the Emphasis noise reduction engaged. Both units are excellent in this regard.

Behringer gives frequency response for the Feedback Destroyer as 20 Hz - 20 kHz, -3 dB (wonder where in the spectrum that -3 dB is?). The Yamaha spec is a puzzler, “20 Hz-20 kHz 0 +/- 1, 0 dB.” That’s exactly how it’s written in the manual; needless to say, something got lost in the translation, as the deviation-from-flat figure doesn’t make much sense. Perhaps they meant 20 Hz - 20 kHz +0 /- 1 dB.

As noted, Behringer lists the BFD’s S/N noise spec as < 94 dBu (which is most assuredly optimistic), while Yamaha uses a peculiar specification of < 76 dBm, improving to 80 dBm with Emphasis. This is a real puzzler, because by all indications dBm is no longer an industry-accepted designation for audio-component specifications. It’s a unit for measuring levels of power in relation to a 1 milliwatt reference signal, dissipated across a 600-ohm load. Modern audio equipment is no longer based on load-sensitive circuits, which is why the dBm reference has not generally been used as an audio specification for at least 60 years. Today dBm specs are more typically seen in radio, microwave and fiber optic networks. By all indications there is no simple way to translate a dBm noise specification to a dBa or dBu value more typically seen with modern audio equipment. Even querying the knowledgeable folks at the AVS Forum did not get a definitive answer. The best they could tell me with was that 76 dBm translated to a dynamic range of about 100 dB – which of course is not quite the same as a S/N figure. It’s a shame Yamaha didn’t give us a viable S/N spec, because my crude tests show that the YDP2006’s background noise levels are vanishingly low.

Measurements with Room EQ Wizard
Loopback measurements with Room EQ Wizard showed baseline response with the equalizer bypassed to be ruler flat from 20 Hz - 20 kHz, +/- fractions of a decibel – even better than the +/- dB variation Yamaha’s obfuscated specs imply. Subsequent measurements with the equalizer engaged, but with all filters set for unity gain (i.e. no boost or cut), delivered perfectly identical measurements to the graphs shown below, indicating that the YDP’s filters cause no effect until the gain knob is moved from 0 dB – as it should be. Listening tests also confirmed the transparency of the YDP2006 with its filters bypassed.

Strangely, I noticed minor differences in baseline response at the frequency extremes with measurements taken with my current Dell laptop vs. the antique Compaq I used to use. Figure 1 shows the Dell; Figure 2 shows the Compaq. The same soundcard, a TASCAM US-122L, was used with both. Frankly I have more trust in the Compaq measurement; I have a hard time believing an equalizer of this caliber doesn’t make it out to 20 kHz.

Seeing these discrepancies is surprising, and it sure raises some flags. Anyone who frequents our REW Forum has seen plenty of soundcard calibration graphs similar to these, showing fairly flat response across the frequency spectrum but with irregularities at the frequency extremes. Granted, we’re talking about fractions of a decibel here – nothing remotely audible – but it makes me wonder if the high end aberrations aren’t simply an anomaly with either REW or the computers themselves. It just seems too strange – and too much of a coincidence – that so many sound cards and components would show “squiggles” in response at the low or top end. It’s just hard to believe they would all be like that. I’m guessing that our measurement platform and/or hardware just can’t reproduce it accurately for some reason.

Figure 3 shows parametric filter characteristics. A filter set for 1000 Hz and boosted 3, 8 and 12 dB shows precisely those value on the graph; as can be expected from a digital equalizer, the YDP2006 is dead-on accurate. The graph also shows the Yamaha’s filters are constant Q, which are more desirable than the variable Q filters found with many budget equalizers. Variable Q filters tend to cut a broad path at lower boost or cut values, as seen in Figure 4, and can spread (for example) as much as an octave wide for a 1/3-octave filter. Yamaha’s filter does appear to spread a bit wider with a 3 dB adjustment than at greater gain values (notice that the peak is not as sharp), but I don’t see this as a problem. A small-gain filter can be barely audible as it is, especially in the lower frequencies, so if the filter is too tight it would only serve the make it even less audible. That in turn would probably lead to the application of a more severe boost or cut to compensate.

Perhaps a better option for applying overall boost and/or flattening response below 20 Hz is to use negative-gain filters instead of positive. Figure 7 shows response with two -4 dB filters centered at 20 and 100 Hz with a 2-1/2 octave bandwidth (the YDP’s broadest filter option), along with an 80 Hz low-pass filter that would be commonly used with a home theater receiver. The 20 Hz negative-gain filter counteracts the baseline curve’s natural drop below 10 Hz, and in so doing flattens response below 20 Hz and extends usable extension down to an incredible 2 Hz: Note in Figure 7 that response drops only 2 dB from 20 - 2 Hz, compared to -8 dB for the shelving filter in Figure 6. A more severe cut – say -6 dB or more instead of the -4 dB used in Figure 7 – would flatten response below 20 Hz even more, in case -2 dB at 2 Hz isn’t good enough for you. (Please note that while the dB scaling of Figure 5-8 graphs is different, all show a 60 dB span and therefore are visually compatible.)

Using only the broad 20 Hz filter enacts a 2 dB rise in front of the point where the 80 Hz low-pass starts to roll out, as Figure 8 shows. Thus the second filter at 100 Hz serves to flatten response out to the crossover frequency. The result of both filters used in tandem (i.e. 20 Hz and 100 Hz) is virtually flat response from the crossover frequency down to 20 Hz, as we can see with Figure 7, while delivering (in addition to the aforementioned extension) a 5 dB boost at 5 Hz. Naturally, there would have to be an increase in gain levels somewhere in the signal chain to counteract the inevitable loss from such filters, either at the receiver’s subwoofer output or at the subwoofer amplifier.

Figure 9 shows response for a 20 Hz high pass filter (the lowest setting available), confirming my previous crude evaluation with a SPL meter and sign waves that the HP and LP filters are indeed sloped at 24 dB/octave. Figure 8 shows the same high pass filter with an added broad parametric filter slightly boosted, which serves to push the low frequency “hinge” down to just shy of 20 Hz. I was unable to get an improvement on this with a shelving filter, so those in need of a sub-20 Hz HP filter will probably have to look elsewhere.

Just for grins I thought I’d run the YDP’s notch filters through REW to see what I could find out about them. These filters don’t have any use in a residential system, but are of considerable value in live sound reinforcement situations for eliminating feedback. The filters on this equalizer are a bit peculiar in that they only allow frequency and bandwidth but not negative gain adjustments. As useful as the display screen is for graphing the effect of the parametric filters (as pictures in Post #1 show), what is shows with the notch filters isn’t especially enlightening. As seen in the picture below, with notch filters set for a broad bandwidth the display shows a deep cut; however, at tight bandwidth settings it barely shows a blip. One would surmise from the display that a narrow filter does practically nothing.

REW measurements show that nothing could be further from the truth! I must say I was shocked and awed by the results that came back with these notch filters. I expanded the graph’s lower limit to -60 dB – the lowest setting REW allows – and as you can see in the graphs below, the notch cut is so deep it’s off the chart. Talk about obliterating a feedback frequency! Interestingly, lower-frequency filters don’t cut as deep, as Figure 13 shows, but nevertheless cut far deeper than what can be accomplished with any analog parametric I’m familiar with. Most of them allow only a 15 dB cut at best (although to be perfectly honest I’ve never seen a feedback situation where that wasn’t sufficient).

Figure 11
Notch Filter at 2.1 kHz, 1.4 Q (1 Octave)

Figure 12
Notch Filter at 2.1 kHz, 4.5 Q (1/3 Octave)

Figure 13
Notch Filters at 125 and 2.1 kHz, 10 Q (1/7 Octave)

These superb notch filters afford the YDP2006 flexibility unparalleled by any analog parametric equalizer I’ve ever used for live sound reinforcement. For instance, if you’re having feedback issues you can easily burn two or three filters taking care of it, leaving only one or two left for any general equalizing you might need to do. With the YDP2006 you could use four notch filters for feedback – it would be unusual to need more than that – and still have all six parametric filters available for dealing with room response. Awesome! Of course, all that is doubled if you’re using it as a mono equalizer. I sure wish I’d had this baby back when I was the soundman at my kids’ school for all their commencements, Easter and Christmas programs. The timid little kindergarteners and first graders had such soft voices I had to crank the mics to the moon to pick them up, which of course meant I had lots of feedback frequencies to deal with. I was using a TDM Audio 30GE-2 at the time, an superb analog 1/3-octave EQ with three notch filters on board, and I’d still end up using a few of the third-octave filters on top of notch filters. The YDP2006 operating in mono would have eight notch filters to deal with unusual situations like this. The high pass filter could also be useful as well: Since there’s no appreciable content in children’s voices below 2-300 Hz, a filter set in that range would effectively eliminate any and all potential feedback frequencies below that point.

Set-Up and Operation
Since the YDP2006 only has XLR connections (not uncommon with pro audio equipment), it will require XLR-to-RCA cables for use in a traditional domestic system. If you don’t know how to make your own, you can find such cables at Monoprice for very reasonable prices, or your local guitar shop. For those unfamiliar with XLR connections, they have male and female plug ends. You will need a pair of each if you intend to use the YDP in its stereo configuration.

Once you get the XLR to RCA cables, it wouldn’t hurt to verify that they are wired correctly. This is easily done with an ohm meter, or by removing the cover from the connectors for a visual inspection. The RCA’s center pin connection should go to the XLR’s pin 2 (signal [+]), and the RCA’s sleeve (aka shield) to the XLR’s pin 3 (signal [-]). Typically you will find a jumper between pins 1 and 3. If you get some hum or noise, try disconnecting the Pin 1-3 jumper.

After the Yamaha is hooked up to your system, the first thing you want to do is set it up for the type of operation you would like. The YDP2006 can be used as a mono EQ with twelve filters or a stereo EQ with six filters per channel. Either mode can be set for a +/- 6 or +/- 12 dB boost/cut range. But contrary to logic, there is no global setting for these basic parameters. Instead, the YDP’s individual memory slots come from the factory pre-programmed with different variations of these settings: Scroll through the 40 memory positions (using the arrow-up and -down keys), and (if the previous owner didn’t go hog-wild re-naming them all) you’ll see grouped banks pre-labeled with titles like “Stereo 12 dB mode,” “Mono 6 dB mode,” etc. Select one of these memory settings and the equalizer will operate as its title says.

The easiest thing to do is simply chose a memory that’s pre-set for the way you want to use the equalizer (presumably most of us want stereo or mono, +/- 12 dB operation). However, any memory slot can be easily reconfigured in the Utility menu. You might naturally think this would be done on the “System Set-Up” page. Nope, that would make too much sense! It’s done on the “Parameter Copy” page. Use the “F” knob to select the mode or “template” you want (as the manual calls it) – Stereo 6, Stereo 12, Mono 6, or Mono 12) – and press “Store.” If you select the Mono template, you will need to execute an additional step on the “System Set Up” page, choosing the Left or Right inputs/outputs for your connections.

Please note that changing the mode of operation has no bearing on the memory TITLE that appears on the display when you call up that memory slot. So even if you change a “Stereo 6 dB” memory setting to “Stereo 12 dB,” it will still show “Stereo 6 dB” when you recall that memory. So you will probably want to re-name the memory title. This is accomplished on the “Title Edit” page in the menu (at least that one is logically labeled).

Our System in 2007 with YDP2006 as Subwoofer Equalizer

Fortunately, once you set up the memory slot(s) and template you intend to utilize, operation of the equalizer is pretty straightforward, especially if you have some experience with analog parametrics. But even if you’re a parametric novice, you can get “educated” pretty quickly on how the filter parameters work by simply playing with the knobs and watching the nifty display, which shows in “real time” what happens when you manipulate the frequency (F), gain (G) and bandwidth (Q) knobs.

Filter parameters and all other adjustments can be set for the left and right channels independently, or both channels simultaneously. Simultaneous adjustment is accomplished by pressing the Left and Right buttons together. As mentioned previously, pushing the “PEQ” button twice will allow you to access the digital attenuation and delay functions, and the “Notch” button will access the low and high pass filters, if you have a use for them, and they can be set independently or simultaneously as well.

Subwoofer Use
The astute reader may have noticed that I have repeatedly said that the Yamaha’s filters can be set for “virtually” any frequency. It’s here we see a downside to digital parametric equalizers compared to analog: They can only set filters at pre-programmed frequency “stops,” unlike an analog parametric EQ which can truly center a filter on any frequency. The same is also true of both equalizer types for bandwidth and gain settings.

In this regard not all digital parametrics are created equal. Its accuracy – i.e., ability to set precise filters – will depend on the number of frequency and bandwidth settings it’s designed for. In this regard the Yamaha takes a back seat to the BFD. It only has 53 available frequency stops between 20-90 Hz, the primary range for subwoofer equalization, while the Behringer DSP1124 and FBQ2496 models both offer 131. This translates to 1/24-octave resolution for the YDP2006, while the BFD’s resolution is substantially greater at 1/60-octave.

Similarly, there are only 8 available bandwidth settings between the Yamaha’s highest (i.e., most narrow) 10 Q setting (~1/7-octave) and 4.5 Q (~1/3-octave), which is about as wide a filter as most people will ever use for a subwoofer. By comparison, the DSP1124 allows for 14 bandwidth settings between 11.5 Q (1/8-octave) and 4.5 Q. (Distressingly, the FBQ2496 has a mere five bandwidth settings between ~1/7 and 1/3-octave.) To its dubious credit, the YDP2006 does allow for gain adjustment in 1/2 dB increments – not that many will find that terribly useful.

Needless to say, it was highly aggravating to find that such a high-priced equalizer is less precise than the lowly DSP1124. Initially, at least. A little experimenting with a pink noise signal showed that each incremental frequency and bandwidth setting resulted in a change in sound that was only barely audible. So while 1/24-octave resolution does not look as good on paper as 1/60, from a functional perspective it’s perfectly adequate.

It’s peculiar that Yamaha didn’t allow for tighter bandwidth settings than 1/7-octave. Most analog pro-audio parametrics will get down to 1/10 or even 1/20-octave bandwidths, which is great for precisely excising feedback frequencies in PA systems if the equalizer doesn’t have dedicated notch filters. Fortunately that’s not a concern for the domestic user, and there should seldom be a need for a filter tighter than 10 Q for subwoofer equalization anyway (as explained in my Minimal EQ article). Nevertheless, fans of modal subwoofer filtering, which often utilizes narrow notch filters and requires precise frequency centers in pursuit of the best-possible-looking waterfall graph, may find this equalizer unacceptable.

I initially had some difficulty equalizing my subwoofers using REW’s low frequency sweep because the program does not support this equalizer, and as such cannot create accurate filter recommendations for it. Therefore it’s best to use REW’s RTA feature for equalizing your subwoofer. Even with the YDP having less resolution than the BFD, it was no problem getting the response curve and sound I was after.

Some of the YDP’s features may make it an attractive low-cost option to the DIY speaker and subwoofer folks. The shelving filter, for instance, will extend below 20 Hz, a benefit which most digital EQ’s do not have. We occasionallly see people on this and other Forums asking if the BFD can be set up for a high-pass or low-pass filter. Not very effectively, but the YDP2006 can do both of these things. Also, the ability for the digital delay to be finely set for fractions of an inch will be useful for time-aligning the drivers in some infinite-baffle manifolds, as well as the individual drivers of a DIY full-range speaker.

Full-Range Use
Although I bought the YDP for subwoofer duties, and I typically frown on digital gear in my main-channel analog signal chain, I thought I would insert it across my front L/R channels just for grins, not really expecting much good to come of it.

To begin, I performed a few crude experiments that I usually run on equalizers to help determine if they are decent quality (or not). One of those is what I call the “pink noise test.” Pink noise is an unforgiving signal source that can reveal subtle changes in timbre that are easily missed with program material. With all filters set to flat, a good equalizer should add nothing audible to the signal. Playing pink noise through the speakers and switching the equalizer in and out, with all filters set to zero gain, there should be no change in timbre. If there is, then the equalizer is coloring the sound, and it shouldn’t do that until you apply a change in gain to a filter. The YDP passed this test with flying colors, delivering no audible change in timbre.

Another little test I like to do shows if the equalizer has a sufficiently quiet noise floor. This involves turning the receiver’s volume all the way up, with no signal source connected (e.g. an unused input) and switching the EQ in and out, once again with all filters set to flat, to see if it adds any background noise when engaged. (Naturally, great caution is required for this – don’t forget to run the volume control back down before feeding the system an audio signal!)

A second part of this test looks to see how much noise is added when a boosted filter is engaged. Since any boosted filter adds noise, from a purely technical standpoint the EQ’s background noise should only increase in an amount equal to what the filter is adding, and nothing more.

Starting with the rear-panel switches in the -20 dB consumer-level position and all filters bypassed, the YDP exhibited no audible hiss in my speakers with the system volume turned all the way up. I had to put my ear right up against the tweeter to hear anything at all – or rather, nothing at all.

Adding a +12 dB 1/3-octave filter at 6 kHz brought the noise up from dead silent to just barely perceptible – again, with ear to tweeter. Basically, a filter boosted by 12 dB got at most only a few dB in increased noise – certainly nowhere near a 12 dB that should have occurred. This means the Yamaha’s noise floor is considerably lower than the rest of my system, which is pretty well dead-quiet. This is remarkable performance. By comparison, my reference AudioControl C-131 equalizers introduced noticeably more noise with a 6.3 kHz filter boosted 12 dB.

Switching the YDP over to the +4 dB pro setting, again with all filters bypassed, the YDP did exhibit some noise, slightly more than the AudioControls bypassed. It was nonetheless barely perceptible; you had to have your ear right up to the tweeter to hear it. Certainly nothing that would be remotely audible under normal listening conditions. Engaging the Emphasis noise reduction feature brought the +4 dB-setting noise level down to parity with the AudioControl EQs, but not as good as with the -20 dB setting.

Adding a +12 dB filter at 5 kHz in +4 dB mode increased noise only slightly, once again nowhere near the 12 dB increase that should have occurred. Keep in mind that in with the +4 dB pro setting, the equalizer now had a smidge of audible background noise, which means it was now somewhat above the noise floor of my receiver. Thus, a +12 dB high frequency filter should have added as much noise as the C-131 equalizer did. But it didn’t. Suffice it to say, this is a remarkable phenomenon.

With the YDP’s noise attributes firmly established as “outstanding or better,” I turned my attention to equalizing my front speakers. I was not set up for full-range REW measurements at the time, so I used my trusty AudioControl R-130 1/3-octave real time analyzer.

My speakers are a bit soft above about 6 kHz, and with my AudioControl C-131 EQs it required boosting most of the filters above that point 2-5 dB to achieve flat response out to 20 kHz. So the first thing I did with the YDP2006 was correct that. Setting the YDP’s #6 filter for high frequency shelving, boosted 6 dB with a turnover at 5.3 kHz did the trick.

My right front speaker is near a corner, while the left one is not. Naturally, the RTA showed different readings between the two speakers in a few places below 400 Hz. The YDP allowed me to match their response more precisely than I had been able to with my 1/3-octave equalizers. At least one problem in need of adjustment for one speaker was precisely between the 100 and 125 Hz LED indicators on the AudioControl RTA. It was never possible to correct this problem with my 1/3-octave equalizers; pulling down the 100 and 125 Hz sliders always resulted in the LED’s on either side of those two frequencies (i.e. 80 and 160 Hz) dropping as well. In other words, trying to fix one problem only caused another. With the YDP2006 I was able to set a filter at 112 Hz – squarely between 100 and 125 Hz – with the precise bandwidth to lower the 100 and 125 Hz LEDs back in line with the rest. Behold the power of a parametric equalizer!

I was also able to fix another nagging problem I’ve had in my system. Well, not so much the system as the room. My favorite location on the couch unfortunately puts the left speaker a bit closer to me than the right. So, the left speaker naturally sounds louder at that listening position. Most people do not know that proper delay can fix this problem. That’s right – the closer speaker sounds louder because there is a time-alignment problem, not because it’s physically closer. Dialing the proper delay setting for the left channel restored the L/R volume balance without a gain (SPL) adjustment. (Of course, this exercise is largely moot with modern receivers’ auto calibration capabilities.)

Naturally I wasn’t surprised to find that I could get a RTA reading that looked better with a parametric EQ than I could obtain with the AudioControl equalizers. But I’ve been fooling around with high-performance equalizers long enough to know that what looks better on a real time analyzer display (or a computer-generated frequency response graph) doesn’t necessarily translate to improved sound quality.

The real surprise came when I fired up the CD player for some listening tests (yes, I still have one of those things). Daisy chaining the AudioControl and Yamaha equalizers made it easy to switch between them for fairly instantaneous A/B comparisons. I wasn’t expecting any difference worth mentioning, or if anything that the C-131s would handily dust the Yamaha, just as they had bested every other equalizer I had pitted against them over the years. After all, the Yamaha was saddled with those A/D-D/A conversions in the signal chain – it didn’t stand a chance. Right?

Well, imagine my surprise to find that the highs sounded cleaner with the Yamaha! Nothing drastic, mind you. I had to switch back and forth between the two equalizers a few times to make sure I was really hearing something. It was subtle, but definitely and noticeably there. Sure, the soft highs in my speakers sounded better with the AudioControls' switched in than bypassed. But changing over to the Yamaha, the highs were definitely more clear and clean. The only way I can describe it is, the highs with the AudioControl EQs sounded slightly veiled compared to the Yamaha. Clearly, the C-131's had finally run up against an equalizer they couldn’t put to shame.

The main thing I would attribute the Yamaha’s improvement in sound quality to is the fact that it was able to accomplish the high frequency adjustment my speakers needed with a single filter, while it took five to accomplish the same thing with the AudioControl EQs. Further evidence that minimal equalization is always preferable. If you believe equalizers are always detrimental to main-channel sound quality, the YDP2006 sounds like there is no EQ in the signal chain at all.

And another surprise: I mentioned above that with its back-panel switches set for +4 dB, the Yamaha was not as quiet as the AudioControl equalizer. That was with all filters set flat for both equalizers. But, in actual use, with filters engaged for both equalizers, the Yamaha actually ended up being quieter than the AudioControl EQs! This can be attributed to the fact that (as mentioned) the YDP’s filters generated considerably less noise than the C-131, and that fewer filters were ultimately used. Which is great, because I found I had to keep the Yamaha in the +4 dB position. In the -20 dB position I could drive it into clipping during demanding movie passages. A side benefit of keeping the YDP in +4 mode is that you’ll probably never be able to drive it into clipping, making the use of the digital attenuator unnecessary.

I noted at the beginning of this Section that I hooked up the YDP2006 to my mains just for an evaluation. The rest of the story: It stayed in my system. That’s right, I never took it out. I resurrected the BFD back to subwoofer duties and promptly retired my AudioControl EQs. I sold them on ebay and bought two more YDPs for my HT system, one for the subs and one for the center channel. Suffice it to say, I can’t say enough good about the Yamaha YDP2006. It’s hands down the finest equalizer I have ever used, easily worth 3-4 times what they typically sell for. The ebay seller I bought my first one from, who raved about its sonic capabilities, knew what he was talking about!

Answering 20-Bit Critics
Naturally, there are some who will vilify the YDP2006 for its outdated A/D-D/A converters. I call them 20-bit critics, but two-bit might be more accurate because it’s highly doubtful these folks have actually laid a hand on this fine equalizer, much less heard it. I can assure the reader that any criticism of this sort has no merit, for any number of reasons.

For starters, it’s generally accepted in the professional recording field that a 16-bit waveform, which has 65,536 amplitude or quantization “steps,” is considered the threshold of what is acceptable for hi-fi sound, because at that bit depth the human ear can no longer detect quantization errors at low levels. While there may be some debate about that in audiophile circles, the potential quantization available with 20-bit converters like the YDP has is 1,048,576 amplitude steps – well over a dozen times greater than that of a 16-bit converter.

And here’s a little tidbit not widely known: No A/D converter actually performs at its “named” bit depth. For instance, 16-bit converters are doing good to have an actual 14- or 15-bit performance; the other data bits are lost to noise and distortion for various reasons that don’t bear discussion here. And distressingly, this loss increases disproportionally as bit depth increases: Twenty-bit converters might get only 16- or 17-bit performance, and 24-bit is doing good to deliver a mere 18-bit performance. Fortunately, the threshold of hearing is only 14-bit (the real-world downgrade of A/D converter performance is certainly reflected in the professional recording industry’s 16-bit edict mentioned in the preceding paragraph).

Other functional realities force limitations on both the analog and digital side of performance specifications as well. For instance, using the example of 24-bit A/D converters because it’s easy to find information on them: If they were really able to deliver the 147 dB dynamic range they theoretically are capable of, they would have to be able to resolve signals as small as one billionth of a volt! Naturally, they can’t do that. On the analog side of things, down in this range transistors and resistors produce noise just by having electrons moving around due to heat. So even if A/D converters could be designed to resolve such low levels, the low-noise requirements of the other circuitry in the component – power supplies, balancing ICs or transformers etc. – would be so stringent that they would either be impossible to build, or too expensive.

By comparison, 20-bit converters have a theoretical dynamic range of “only” 122.5 dB, but even that figure appears to be beyond the reach of even the best modern A/D converters and circuit design. Dig through the manuals of any number of professional-grade 24-bit processors, no matter what the price, and you’ll find that the best dynamic range spec they can muster is between 105-115 dB. That puts the YDP’s 106 dB dynamic range spec right in range with “superior” 24-bit processors.

So don’t be concerned by the Yamaha’s “outdated” A/D converters; the quality of the converters in actual use makes a big difference, in addition to the rest of the circuitry in a component. This is why some 24-bit pieces, such as the BFD and Electrovoice DC-ONE (as seen in this thread), are unacceptably noisy. By contrast, Yamaha did their homework. As far as I can see, the YDP2006 easily meets or outperforms its published specs. Remember, this was a third-generation product for Yamaha. The fact that they had the brass to introduce a 16-bit equalizer in 1987 (which incidentally was also extolled for its pristine sound, from what I can find) shows they know a thing or two about quality converters and circuitry.

Summary
Is the YDP2006 a worthwhile improvement over the ever-popular BFD? For subwoofers, probably only if you really hate the Behringer’s looks and/or want something easier to use, and don’t mind taking the time to seek one out or paying the extra expense.

But for full-range use – it’s worth it! After using the Yamaha YDP2006 full-range and exploring its performance and features, I can see why its price was so high. Quite simply, I would regard the YDP as a high-end equalizer that blows away the best analog models I’ve ever used. Indeed, I had to reconsider my long-standing “no digital equalizers in my analog signal chain” stance. You could pay considerably more than double the $150-200 price these usually sell for on ebay and still get a fabulous deal.

Reviewing the Yamaha’s strong and weak points, compared to the Behringer DSP1124 (FBQ1000):

Strong points

Aesthetically more attractive than the BFD if the rest of your equipment is black.

Intuitive, user-friendly interface similar to an analog parametric.

Easy-access filter controls, including on/off switches for each filter with LED indicators showing which filters are active.

Pristine signal path – clean enough for use on main channels, probably for all but the most expensive systems (and I would be surprised if it didn’t shine there, too).

Weak points

More expensive than the BFD.

Somewhat unintuitive Utility menu.

Not as precise as the BFD.

Fewer filters available.

Combination of 13” depth, plus XLR connectors, may pose a problem in some equipment racks.

Can run a bit hot.

XLR inputs only.

Rack ears are not removable.

Large backlit LCD screen may be a distraction in some installations.

Bottom line: A superb equalizer at a bargain price that successfully combines the best of analog and digital worlds.

Shop smart
There are a few things to look out for when buying a used YDP2006. One is “wonky” encoder knobs. When they’re functioning properly, you should see a change in the display for each click-stop when you turn the knob. If the displayed setting jumps around, or delivers counter-intuitive changes (like the values decreasing when the encoder is turned clockwise), then the encoder – and hence the equalizer – is defective.

If the EQ won’t retain its settings then you unplug it or turn it off, that’s a problem. As mentioned, there is an internal battery that maintains the settings. It is easily replaced by removing the top cover (be sure the EQ is unplugged). If you replace the battery, or can verify with a volt meter that it is good, then the EQ should retain all settings when unplugged or turned off. If not, the equalizer is defective and should be returned: Needless to say, if you have to re-set every filter and function every time you power up, for all practical purposes the equalizer is useless.

Our System in 2012 with YDP2006 for Subwoofer, Main and Center Channels

Another thing to look out for is bent or cracked rack ears. Since the YDP2006 has a heavy and deep chassis, it requires some kind of underpinning or rear support if mounted in a professional equipment rack. If it did not get such support, the ears will bend and/or crack under the weight of the unit – especially if it was used in a mobile sound reinforcement rack. Naturally, this has nothing to do with the actual function of the equalizer; it just looks a bit shabby. Another rack-ear clue that the equalizer might have had a rough life is lots of “rack rash” around the mounting holes. You can expect to find some scaring around the rack ears if plastic or cardboard washers were not used in front of the rack screws, but excessive rack rash is an indicator that the unit was moved in and out of a lot of racks, which in turn is a sure indicator of a rental unit or one that saw life on the road in touring systems. Again, this doesn’t necessarily mean it won’t serve you well, as the YDP is a fairly rugged piece of equipment. The rash can always be glossed over with a black marker and it will barely be visible with normal room lighting.

All things considered you want to find one that has been used in a permanent installation, if possible. Such equipment has a pampered life compared to those used in mobile racks. However, these can be difficult to find, but if aesthetics are important to you it may be worth the wait.

Miscellanea
The YDP can have some cooling issues. The left side of the back panel functions as a heat sink for the power supply voltage regulators, so it generates some heat. It’s not an issue normally, but it’s not a good idea to stack multiple units in your system unless you use external cooling, or put an inch or two of space between them.

However, external cooling comes with its own downside. With a fan blowing on the backside of the YDP2006, eventually the +4/-20 dB operating-range switches will get dirty. When this happens you’ll hear sudden and drastic increases or drop-outs in volume. It’s an easy fix, fortunately: Just pop the top cover and shoot a bit of tuner cleaner into the switch body, and move the switch back and forth a few times to work it in. The best way to avoid this problem is to keep some space between them when stacking multiple units, so that external cooling won’t be necessary.

This isn’t in the manual, but if you ever find a need to restore the Yamaha to its factory settings, press the L + R + Bypass buttons simultaneously while turning on the power.

Another tidbit you won’t find in the manual that some will find useful: When in 12-band mono mode, the YDP will send the input signal to both outputs. So if you have two subwoofers, no need to split the output to them with a “y” adapter.

Even though the YDP2006’s LEDs are not as bright as the BFD, I personally I found them too bright for my taste, as well as the LCD screen. I darkened the filter on/off indicators with a black Sharpie, and the function button indicators with a broad-tipped Marks-a-Lot. For the LCD screen, I installed a piece of 35% window tint.

And finally, if you don’t like the rack ears, I have a solution: Cover the holes with black electrical tape, as seen in picture above with both the equalizers and Carvin amplifier. 3M Super 88 electrical tape has a satin finish that is practically invisible on black components, even with daytime lighting, and you can get it at any big-box hardware store. You can buy cheaper electrical tape, but don’t bother. I haven’t seen another brand that holds up over the years and doesn’t come loose, leaving a sticky mess behind. I’ve been using it for years to hide the “billboards” many components have on their faces – such as the Yamaha receiver in the picture above. Just line up a piece of the tape with the edge of the rack ear and trim the top and bottom with a single-edge razor blade.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. | To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

Sorry to say this is my first review to read from you. Great thorough and very in depth review. Awesome to see older models out there can do what 99% will need for their home audio requirements. I am always searching on ebay for used equipment in pro audio.

I have always been wanting to have a M.E. EQ or WM8 for my subwoofer system but glad to see there are other options out there.

"Music is the space between the notes"
“[T]o talk well and eloquently is a very great art, but that an equally great one is to know the right moment to stop.”

Very nice and thorough review Wayne! I've been contemplating trading my BFQ2496 in for an analog PEQ - a Rane PE17 is what I have in mind. Like you, I'm not a fan of the Behringer interface, but the digital units to have advantages. I'm still undecided. Thanks for sharing your experience with the Yamaha. I don't believe Yamaha gets enough credit for how great its audio gear is.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

REQUIRED FIELDS ON THIS PAGE YOU MUST COMPLETE ALL OF THESE

Please enter a password for your user account. Note that passwords are case-sensitive.

Password:

Confirm Password:

Email Address

PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.